Licea M.R.,Celaya Institute of Technology |
Cervantes I.,Graduate School and Research Division ESIME CU IPN
Control Engineering Practice | Year: 2017
This paper introduces a means to evaluate the severity of the lateral skid phenomenon based on a balance of forces applied to the vehicle. Derived from this analysis, a lateral Skid Index (SI) is proposed which, along with the well-known rollover index, is used to monitor the vehicle and to derive an indirect envelope specification. A robust control ensures the accident risk mitigation in spite of model uncertainty and perturbations from the driver. Speed and predictive dependent risk switching criteria are used to activate the control action. The proposed strategy is illustrated using Hardware-in-the-Loop experiments and its comparison with existing strategies is performed. © 2017 Elsevier Ltd
Conde-Mejia C.,Celaya Institute of Technology |
Jimenez-Gutierrez A.,Celaya Institute of Technology |
El-Halwagi M.,Texas A&M University
Process Safety and Environmental Protection | Year: 2012
Lignocellulosic materials, which consist mainly of cellulose, hemicellulose and lignin, are among the most promising renewable feedstocks for the production of energy and chemicals. Bioethanol is a major biofuel that can be produced from lignocellulosic materials. Its production typically involves a hydrolysis-fermentation route, which has three main steps: pretreatment to get fermentable sugars, fermentation to produce bioethanol, and a separation process to obtain highly concentrated bioethanol. The pretreatment step has been recognized as a technological bottleneck for the cost-effective development of bioprocesses from lignocellulosic materials. In this work we analyze the potential of several pretreatment methods for bioethanol production from lignocellulosic materials. Simulations based on stoichiometric relations and yield data were conducted to evaluate the energy requirements of each pretreatment method. Other parameters were also considered such as the cost of chemicals, consumption of water, and constraints on the composition of inhibitors. Performance benchmarks were identifies using targeting techniques and these benchmarks were used to assess the actual performance of the alternatives. The combination of the evaluated parameters with target production values obtained from reported yields served as the basis for identifying the most promising pretreatment options and for defining areas of opportunities. This approach uses limited information, but it provides reliable results in order to reduce the number of pretreatment alternatives. The target production usage gives an estimation of the global process efficiency without the completed flowsheet defined. © 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Gomez-Gualdron D.A.,Texas A&M University |
McKenzie G.D.,Texas A&M University |
Alvarado J.F.J.,Celaya Institute of Technology |
Balbuena P.B.,Texas A&M University
ACS Nano | Year: 2012
Single-walled carbon nanotubes (SCWNTs) have outstanding properties that depend on structural features such as their chirality. Thus, developing a strategy to control chirality during SWCNT synthesis is critical for the exploitation of nanotube-based technologies in fields such as electronics and biomedicine. In response to this need, tuning the nanocatalyst structure has been envisioned as a means to control the nanotube structure. We use reactive classical molecular dynamics to simulate nanotube growth on supported Ni 32, Ni 80, and Ni 160 nanoparticles at various metal/support interaction strengths (E adh). The initial carbon ring formation is shown to correlate to the nanoparticle surface structure, demonstrating the existence of a "template effect" through a dominant occupation of hollow sites. The E adh strength alters the dynamic/structural behavior of the nanoparticle, in turn influencing the interplay between nanotube and nanoparticle structures. For example, the contact region between the nanoparticle surface and the growing nanotube decreases as E adh increases because capillary forces that raise the metal into the nanotube are counteracted by the strong metal/support interaction. The nanoparticle mobility decreases as E adh increases, eliminating a possible inverse template effect but hindering defect annealing in detriment of the nanotube/nanoparticle structural correlation. On the other hand, the contact between the nanoparticle and the nanotube increases with nanoparticle size. However, the heterogeneity of the nanoparticle structure increases with size, reducing the structural correlation. These results suggest that an appropriate combination of nanoparticle size and strength of the catalyst/support interaction may enhance the desired template effect and bias formation of specific nanotube chiralities. © 2011 American Chemical Society.
Hernandez J.A.,Academia de Biotecnologia y Farmacia |
Gomez S.A.,Metropolitan Autonomous University |
Zepeda T.A.,National Autonomous University of Mexico |
Fierro-Gonzalez J.C.,Celaya Institute of Technology |
Fuentes G.A.,Metropolitan Autonomous University
ACS Catalysis | Year: 2015
The activity and deactivation of Au/CeO2 catalysts in the PROX reaction were measured during long-term experiments (TOS = 160 h) by in situ DRS-UV-vis spectroscopy. During the reaction, the support showed a decrease in band gap energy. The activity and selectivity to CO2 were closely linked to the reduction of Aun+ species, the sintering of the reduced Au species, and to changes in the Ce3+/Ce4+ ratio. This ratio increased during long-term PROX experiments, showing a decrement of surface oxygen atoms from the CeO2 phase which participated in the reaction, after which the total oxygen fed to the reaction was wholly consumed. Also, almost all of the Au3+ species initially present in the catalysts were reduced to Au+ and Au0. Results suggest that the activity loss is connected to the fast reduction of Au species and is also linked to changes in the redox properties of ceria, breaking the cycle that provides oxygen to the reaction. Sintering of the Au nanoparticles occurs in a longer time scale. On the other hand, in the case of fresh Au/CeO2 catalysts, the Aun+/Au0 ratio decreased with increasing Au content. This initial ratio affects CO2 selectivity as a function of temperature. © 2015 American Chemical Society.
Gallardo-Alvarado J.,Celaya Institute of Technology
Robotics and Computer-Integrated Manufacturing | Year: 2012
In this work the jerk analysis of a 3-RRPS parallel manipulator to realize six degrees of freedom is approached by means of the theory of screws. The input/output equations of velocity, acceleration and jerk of the moving platform with respect to the fixed platform are obtained systematically by resorting to reciprocal-screw theory. A numerical example is included in order to show the application of the method of kinematic analysis. Furthermore, the numerical results obtained via screw theory are satisfactorily compared with simulations generated with the aid of commercially available software. © 2011 Elsevier Ltd. All rights reserved.
Gallardo-Alvarado J.,Celaya Institute of Technology
Journal of Intelligent and Robotic Systems: Theory and Applications | Year: 2014
In this work the hyper-jerk analysis of robot manipulators is addressed by means of the theory of screws. The reduced hyper-jerk state of a rigid body as observed from another body or reference frame is obtained as a six-dimensional vector by applying the concept of helicoidal vector field. Moreover, this contribution demonstrates that the reduced hyper-jerk state of a rigid body can be considered, similar to the velocity state, as a twist about a screw. Furthermore, the reduced hyper-jerk state is systematically obtained in pure screw form. Finally, a case study, which is verified with the aid of commercially available software, that consists of solving the kinematics, up to the hyper-jerk analysis, of a zero-torsion parallel manipulator is included in order to show the application of the method of kinematic analysis. © Springer Science+Business Media Dordrecht 2014.
Navarrete-Bolanos J.L.,Celaya Institute of Technology
Engineering in Life Sciences | Year: 2012
Fermented foods and beverages are an intrinsic part of our diet. All over the world, regional quality products are produced by native microorganisms in their natural ecosystems, giving the basis for registering appellations of origin. For wines, premium quality products can be obtained by spontaneous fermentation; its success depends heavily on environmental conditions. Inoculated fermentations with selected pure cultures have been developed as alternative; however, the products obtained have a plain aromatic profile compared to those obtained by successful spontaneous fermentations. Several studies have shown that inoculums of native mixed cultures are able to exalt the peculiarities (aroma, structure, and color) of a wine, and preserve their authenticity and uniqueness; however, reliable methods for native microorganism selection are still limited. Currently, the strain selection criterion is based on their genetic endowment; but, the design of an efficient fermentation process requires also knowledge on physicochemical effectors to maximize the metabolic capacity of the selected strains. This article reviews the guidelines for strain selection, and discusses directions for exploring the use of these microorganisms specifying their operating conditions. The main goal of this work is to present the strategy of how to evolve a spontaneous fermentation to directed fermentation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Gallardo-Alvarado J.,Celaya Institute of Technology
Robotics and Computer-Integrated Manufacturing | Year: 2014
In this work a simple method to solve the forward displacement analysis of the general 6-6 fully parallel manipulator is applied. The method is based on generating closure equations upon the unknown coordinates of three points embedded to the moving platform. The method is easy to follow and it is available for both, planar and three-dimensional moving platforms. Numerical examples are included with the purpose to show the application of the method. © 2013 Elsevier Ltd.
Guterrez-Antonio C.,Celaya Institute of Technology |
Briones-Ramirez A.,Innovacion Integral de Sistemas S.A. de C.V. |
Jimenez-Gutierrez A.,Celaya Institute of Technology
Computers and Chemical Engineering | Year: 2011
In this work we use genetic algorithms to optimize Petlyuk sequences using a rigorous design model. A multi objective genetic algorithm (GA) with constraints was formulated and interconnected with the Aspen Plus process simulator to obtain each data point during the search process. In addition to providing more energy-efficient designs than some reported structures, two relevant trends were observed from the results of the case studies; one had to do with the feed location to the prefractionator as a function of the mixture properties, and the other one with optimal structures requiring four interconnecting stages instead of the two normally used for Petlyuk sequences. An application for the separation of azeotropic mixtures is also included. The optimal placement of vapor-liquid interconnections is again shown to be different for each interconnecting stream. The GA showed a robust performance, and was practically independent on the initial values for the search variables. © 2010 Elsevier Ltd.
Flores-Escamilla G.A.,Celaya Institute of Technology |
Fierro-Gonzalez J.C.,Celaya Institute of Technology
Journal of Molecular Catalysis A: Chemical | Year: 2012
TiO 2-supported rhodium samples synthesized from the Rh 6(CO) 16 complex were catalytically active and selective for the gas-phase methanol carbonylation at 140°C and atmospheric pressure in the presence of methyl iodide as promoter. Infrared (IR) spectra recorded during catalysis allowed the identification of molecularly adsorbed methanol, together with linear, doubly, and triply-bridged surface methoxy species on Ti 4+ sites of the support. IR bands characteristic of rhodium complexes that might be regarded as reaction intermediates were also observed, in addition to bands assigned to surface acetate species attributed to the formation of methyl acetate. Our results reveal that only linear methoxy species on Ti 4+ sites react with flowing CO in the presence of CH 3I to give methyl acetate, whereas bridged methoxy species and molecularly adsorbed methanol are only spectators in methanol carbonylation. © 2012 Elsevier B.V. All rights reserved.